Cerebrospinal-Fluid Bicarbonate And Potassium Regulation In Icn Neonates

CSF obtained for evaluation of potential sepsis in 42 ICN babies of B.W. 930-4090 gms. and gest. age 27-42 wks. was evaluated for ≥ and K+ regulation. Total CO2 content was measured. CSF ≥ was compared with plasma values calculated from pH and PCO2 measurements bracketing the time of L.P. in infants with stable acid-base values for 3 hours. CSF K+ was compared with same day plasma values. Three ≥ groups appeared evident within the wide distribution of values. I: A reference group with minimal abnormality where CSF ≥ was greater than expected from adult results. II: A group of infants with sepsis, birth asphyxia or recent severe hypoxia. ≥ values were lower than expected when samples were obtained within 24 hours of the insult. III: A small group (N=3) with severe metabolic acidosis and no sepsis or recent hypoxia that had ≥ values similar to those of Group I. With respect to K+, in 38 of 42 infants CSF values varied from 3.0-3.9 mM/1 while plasma values ranged from 3.1-6.3 mM/1. Our results suggest these infants regulate ≥ poorly when stressed by sepsis, severe hypoxia or birth asphyxia. They regulate CSF K+ very well. (Partially supported by NHLBI grant HL 18351;* supported by NIH RCDA HL 00364.)